The rated current and saturation current of a power inductor are two important parameters that describe the electrical characteristics of the inductor under different operating conditions.
Rated current (IRMS or Rated Current) is the maximum current that an inductor can safely withstand under long-term operating conditions. This current value is based on the consideration of the heat generated by the inductor, that is, the heat generated by the inductor during operation cannot exceed its heat dissipation capacity to avoid damage caused by excessive temperature of the inductor. Operating at more than the rated current for a long time will cause the temperature of the inductor to rise too quickly, which may cause the inductor to deteriorate or even be damaged. Therefore, the rated current is an important parameter to ensure that the inductor works in a stable and reliable state.
The saturation current (ISAT) is the current value of the inductor when the core reaches magnetic saturation. Magnetic saturation means that the magnetic flux density of the magnetic core in the inductor reaches a certain limit value after continuous energization, and further increasing the current will no longer cause the increase in magnetic flux density. When the current reaches saturation current, the inductance value of the inductor decreases, which may cause the inductor to operate unsatisfactorily to meet the design requirements, for example, causing fluctuations in the output voltage. Therefore, when designing the circuit, it is necessary to ensure that the actual operating current of the inductor is much lower than the saturation current to ensure that the inductor can work stably.
In practical applications, in order to ensure the stability and reliability of inductors, the appropriate inductor is usually selected according to the saturation current and temperature rise current (IRMS) of the inductor. The design engineer will choose the smaller of the two as the rated current of the inductor according to the actual application scenario, so as to ensure that the inductor will not overheat or reach magnetic saturation due to excessive current when working.
Overall, both rated and saturation currents are critical parameters in inductor design, and they are directly related to the performance and reliability of the inductor. In the process of selecting and using inductors, these two parameters need to be fully considered to ensure that the circuit can work stably and efficiently.